Photonic Millimeter-wave Generation Beyond the Cavity Thermal Limit

TL;DR

This paper demonstrates a compact, low-noise millimeter-wave generator using silicon photonic lasers phase-locked to a Fabry-Perot cavity, surpassing thermal noise limits and suitable for portable communication and sensing applications.

Contribution

It introduces a novel photonic heterodyne approach with silicon lasers phase-locked to a F-P cavity, achieving record low phase noise in millimeter-wave signals.

Findings

Generated 94.5 GHz and 118.1 GHz signals with phase noise below -117 dBc/Hz at 10 kHz offset.

Achieved low phase noise using existing integrated photonic technologies.

Device volume is less than approximately 10 mL, enabling portable applications.

Abstract

Next-generation communications, radar and navigation systems will extend and exploit the higher bandwidth of the millimeter-wave domain for increased communication data rates as well as radar with higher sensitivity and increased spatial resolution. However, realizing these advantages will require the generation of millimeter-wave signals with low phase noise in simple and compact form-factors. The rapidly developing field of photonic integration addresses this challenge and provides a path toward simplified and portable, low-noise mm-wave generation for these applications. We leverage these advances by heterodyning two silicon photonic chip lasers, phase-locked to the same miniature Fabry-Perot (F-P) cavity to demonstrate a simple framework for generating low-noise millimeter-waves with phase noise below the thermal limit of the F-P cavity. Specifically, we generate 94.5 GHz and 118.1 GHz millimeter-wave signals with phase noise of -117 dBc/Hz at 10 kHz offset, decreasing to -120 dBc/Hz at 40 kHz offset, a record low value for such photonic devices. We achieve this with existing technologies that can be integrated into a platform less than $\approx$ 10 mL in volume. Our work illustrates the significant potential and advantages of low size, weight, and power (SWaP) photonic-sourced mm-waves for communications and sensing.